Simple digital zone system: get the perfect exposure always

There is a lot of zone system tutorials out there, but I want to give you a short and highly practical one. If you want to get a deep understanding, please check for the links at the end of this tutorial.

The theory is this, every tone has a numerical value, at digital we work just 5 integers popularly refered as -2, -1, 0, +1 and +2. Equivalents to zones 3 to 7 at old negative + paper school. If you are beyond them you get pure white or pure black.

What a modern digital camera does, when you use full automatic mode, is to measure light using a multimatrix which involves measuring a lot of different areas of the frame, sometimes prioritizing faces (if the camera can recognize them) and usually under-evaluating the upper parts (as the sky is brighter). Then, camera set settings (aperture and shouter) to keep the tone value at 0, or 18% gray, which is fine for most of the times, the problem is that not all of your photos, and specially the good ones, are made of most common tones distributed at most commons distributions through the frame. Also, when you confront a frame with different lighting, you could prioritize the exposure according to what you want.

In order to get a perfect exposure what you have to do is really easy, just set the measuring to spot, that means that your light-meter will just evaluate a specific spot on the center of the frame, then point that spot to measure the tone you want properly exposured (like a wall, concrete, tee-shirt, etc) and set settings (aperture and/or shutter) to the value of that tone according to the table on the next image. Hopefully, with time, you will memorize the tones values, and you could apply this technique really fast. I am still carrying around printings of this table on my wallet, mostly to give them away to other photographers.

This is my short tutorial about digital zone system. If you want to learn more deeply about the subject, my recommendation is to watch the 90 minutes tutorial of Photoshop Cafe.